連想配列にします。
<?php
$url = "http://weather.livedoor.com/forecast/webservice/json/v1?city=130010";
$json = file_get_contents($url);
$json = mb_convert_encoding($json, 'UTF8', 'ASCII,JIS,UTF-8,EUC-JP,SJIS-WIN');
$arr = json_decode($json,true);
echo('<pre>');
print_r($arr);
echo('</pre>');
?>

では、東京の今日の天気を表示させてみましょう。
<?php
$url = "http://weather.livedoor.com/forecast/webservice/json/v1?city=130010";
$json = file_get_contents($url);
$json = mb_convert_encoding($json, 'UTF8', 'ASCII,JIS,UTF-8,EUC-JP,SJIS-WIN');
$arr = json_decode($json,true);
$time = strtotime($arr[description][publicTime]);
echo "<b>東京:今日の天気</b><br>";
echo $arr[forecasts][0][telop]."<br>";
echo $arr[description]."<br>";
echo date("Y/m/d H:i:s", $time)."<br>";
?>

					


